Mathematics - Trigonometric Ratios & Identities Question with Solution | TestHub

To find $\Rightarrow 2\sin 12°-\sin 72$ 

$\Rightarrow \sin 12°+\sin 12°-\sin 72$

$\Rightarrow \sin 12°+2\cos 42°\sin \left(-30°\right)$  $\Rightarrow \sin 12°-\cos 42°$

$\Rightarrow \sin 12°-\sin 48°$   $\Rightarrow 2\cos \left(30°\right)\sin \left(-18°\right)$

$\Rightarrow -\sqrt{3}\sin 18°=-\sqrt{3}\left(\frac{\sqrt{5}-1}{4}\right)$  $=\sqrt{3}\left(\frac{1-\sqrt{5}}{4}\right)$